Production of anhydrous soda base lubricating greases



Patented May 18, 1954 2,678,918 PRODUCTION OF ANHYDROUS SODA BASELUBRICATING GREASES Arnold A. Bunch, New Orleans, La., assignor, by

mesne assignments, to Shell Development Company, San Francisco, Calif.,a corporation of Delaware No Drawing. ApplicationMarch 20, 1946, 'SerialNo. 6555;887

15 Claims. 1

This invention relates to the production of lubricants and, moreparticularly, to substantially anhydrous soda soap greases containingsmall amounts of the higher polyalkylene glycols, that is, those abovethe trialk 'lene glycol, said glycols being exemplified by thepolyethylene glycols, the polypropylene glycols, the polybutyleneglycols, the polyamylene glycols, and the polyhexylene glycols. The sodasoap-greases of the present invention may contain a small amount of theliquid polyalkylene glycols having a molecular weight varying betweenabout 200 and about 600, or a solid polyalkylene glycol having amolecular weight varying from about 1000 to 7000.

It is known that soda soap greases are-exceedingly sensitive to rapidcooling from a highly heated liquid state to a solid state. This hasmade it necessary to slowly cool the grease from its hot liquid stateadjacent its melting point and higher in a period usually varying from12 to 16 hours when cooled in layers of three inches to five inches inthickness, bleeding of the oil from the grease being inhibited duringthis cooling period. In accordance with the present invention quickcooling is accomplished, and bleeding is prohibited by incorporating inthe grease a small amount of a higher polyalkylene glycol thereof havingthe character set forth and cooling in the presence thereof, thepercentage of polyalkylene glycol present in the grease ranging fromabout 0.05% to 1% and preferably from 0.1% to 0.25% or 0.3% taken on theweight of the grease, said cooling being preferably in thin layersaveraging fromto about in thickness. Greater amounts may be used but arenot necessary to accomplish the purpose of the present invention.Desirably, the amount of the polyalkylene glycol incorporated in thegrease should not materially decrease the melting point of the grease.Some decrease in the melting point of the grease for certain purposeswill not be harmful.

An additional object of the present invention is to prepare a completelyreversible soda soap or soda base-grease; said grease having been cooledslowly, or quickly within the spirit of the invention. A grease .isdesignated a reversible grease if it is characterized by the property ofbeing capable of being repeatedlymelted to a liquid state and cooledto asolid state without any change in texture and mechanical properties, anycooling rate being utilized. When the polyalkylene glycol, and,particularly, polyethylene glycol is added in amounts less than about 1%taken on the weight of the grease, the soda base grease becomesreversible. While the amount of polyalkylene glycol added may vary fromabout 03 to 1%, it preferably varies from about 0.1% to .25% or 0.3%taken on the weight of the grease.

In the manufacture of sodium soap greases.

in order to impart mechanical stability to the grease, and to diminishthe tendency of the rease to bleed, it has been necessary to add to thegrease 0.3% to 1% of sodium naphthenate based on the weight of thegrease. It is an object of the present invention to producesubstantially anhydrous sodium soap or sodium base greases which aremechanically stable and which show substantially no tendency to bleed,by incorporating in the grease from about 01% to 05% of a polyalkyleneglycol of the character herein set forth. When an amount varying between03% and 05% of a polyalkylene glycol of the character herein set forthis incorporated in the grease. the latter is reversible to the extentthat it will not disintegrate on rapid cooling down, but the resultinggrease is considerably harder than the worked grease. When 05% of apolyalkylene glycol is incorporated in the grease, the latter becomescompletely reversible, and with this amount or a greater amount of thepolyalkylene glycol present in the grease, the latter becomes capable ofbeing quickly cooled; that is, within a time substantially less thanusually employed and preferably less than two hours when the grease iscooled in layers varying between about inch and about 3 inches inthickness. When the polyalkylene glycol is present in excess of 05%taken on the weight of the grease, an easily pliable grease is obtainedeven on instantaneous cooling.

In accordance with the present invention, the higher molecular weightpolyalkylene glycols of the character herein referred to and, moreparticularly, the polyethylene glycols, are added to lubricating greasesof the anhydrous soda soap or soda base type during or after the cookingoperation, and the resulting greases may be cooled from their liquidstate at extremely rapid rates of the'character herein set forth withoutany deleterious effect on the physical or chemical properties of thegrease, that is, there is no bleeding of the grease, the latter, undercertain circumstances, becoming completely reversible.

The invention will be illustrated by the following examples:

, Example 1 The following ingredients are mixed and cooked:

Grams Stearic acid 200 (3.35%) Hydrogenated castor oil 35 (0.58%)Polyethylene glycol (1500 molecular weight) 10 (0.166%) Coastal paleoil, 100 vis 500 (8.35%) Sodium hydroxide 32 1 or (535%) Metallic sodium18.5 Coastalpale. oil, 100 vis 630 (10.5%) Coastal red oil, 2000 vis4600 .(76.519%) The stearic acid, hydrogenated castor oil, polyethyleneglycol, the coastal pale oil, and the saponifying agent, either sodiumhydroxide or metallic sodium, are all mixed together and the temperatureraised to 360 F. until the reaction mass assumes a syrupy appearance.There is then added additional coastal oil and additional red oil, andthe temperature is maintained at about 360 F, while stirring until asubstantially completely homogeneous mass is obtainable. The hot greaseis then poured into a pan of any suitable size, as for example, a panmeasuring 24" by 60", the depth of the grease layer being A cold streamof air is played upon the grease until the grease solidifies.

There is produced a non-bleeding transparent chassis grease of excellentmechanical stability having the ASTM worked penetration of 296decimillimeters after 60 strokes, and 318 decimillimeters after 300strokes. The resulting grease had a melting point of 348 F., and acidityequivalent to 0.08% oleic acid.

Example 2 The following ingredients are mixed and cooked following theprocedure set forth in Example 1:

Grams Stearic acid 390 (6.6%) Hydrogenated castor oil 8 1 (1.42%)Polyethylene glycol (molecular weight 600) 12 (204%) Metallic sodium ll(58%) Coastal pal oil, 100 vis 720 (12.2%) Coastal red il, 2000 vis 4800(788.96%)

The following ingredients were mixed and cooked together:

Grams Hydrogenated fish oil fatty acids 200 (7.1%) Caustic soda 28(0.985%) Neutral parafiinic oil, 200 vis. at

100 F 1220 (43.0%) Paraflinic bright stock (aircraft lubricating oil),120 vis. at

210 F 14.00 (48.775%) Polyethylene glycol, molecular weight 1500 -1 4(14%) After cooking the above grease to between 360 F. and 375 F., thegrease was poured into a pan of 78 in depth and cooled in a cold airstream. A stable reversible grease was produced having a melting pointof 358 F.

The grease had an ASTM penetration, after 60 strokes, of 305decimillimeters, and after 300 strokes, 328 decimillimeters.

In each of the above examples, the grease assumed a temperature of about95 F. within twenty minutes after pouring into the cooling pans, thesurrounding air having a temperature of about 75 F.

A specimen was taken from each of the batches set forth in Examples 1,2, and 3 and poured onto a steel plat in a layer having about thickness.These specimens cooled from the batch temperature of about 360 F. to 375F. to room temperature in about ten minutes, and the resulting greaseswere stable, reversible, did not bleed, and, in general, had goodphysical and mechanical properties, the penetration and the meltingpoints of the respective greases being as hereinbefore set forth inconnection with Examples 1, 2, and 3.

In order that the description of the cooling step be standardized, itmay be stated that in accordance with the present invention, a greasewill cool from between 300 F. and 400 F. to about F. to F. in about fiveto twenty minutes when a specimen of the grease is poured on a steelplate at a temperature varying between 300 F. and 500 F. in a layerhaving a thickness of The above set forth grease, containing from .05%to 1% of a polyalkylene glycol, is a completely reversible grease,thereby distinguishing from all prior known soda base greases which,although they were mechanically stable and, had a relatively highmelting point, were not reversible; that is, the prior art soda basegreases could not be melted and cooled for a plurality of cycles, as forexample, four to fifteen cycles and/or at any rate of cooling withoutchange in texture and mechanical properties.

The method of incorporation of the polyalkylene glycols into the sodabase greases is not limited to the cooking procedure disclosed inconnection with Examples 1 and 2, said procedure being set forthprimarily for the purpose of illustration and not by way of limitation,said batches being illustrative of standard batches, and the procedurebeing illustrative of the standard procedure used in the production ofanhydrous soda soap or soda base greases. Therefore, in carrying out thepresent invention, any of the prior art grease cooling procedures may beemployed, and the grease may be mixed and cooked through a wide range oftemperatures varying from room temperature; that is, about 68 F. toabout 500 F. The polyalkylene glycols, in percentages ranging from 0.01%to may be incorporated prior to cooking, or during cooking, or they maybe incorporated in a soda base grease which has already been preparedand cooled by melting the grease and mixing it with a polyalkyleneglycol of the character herein set forth, namely, one having a molecularweight between 200 and 7000.

Most of the herein described polyalkylene glycols are oil soluble. Theymay be, therefore, dissolved, directly in the oil. However, thepolyalkylene glycols may be brought into aqueous solution, or an aqueousemulsion may be formed thereof and the grease cooked in the presence ofthe aqueous emulsion provided all of the water is substantiallyeliminated or evaporated out of the grease during the cooking operationor thereafter so that there is produced a substantially anhydrous sodasoap or soda base grease. By a substantially anhydrous soda soap greaseis meant one that has a water-content of less than about 0.2% to 25%based on the weight of the grease and preferably has a water-contentvarying from less than .01% to 0.1%.

The following examples illustrate the manufacture of soda base or sodasoap greases which are characterized by excellent mechanical stabilityand show substantially no tendency to bleed.

areas-raisepreviously pointed loutgl to diminish the tendency of sodabase greasesto bleed, it=has been customarytoadd :5 to 1% of I sodiumnaphthenate. Inaccordance-with the present invention, muchsmalleramounts: of polyalkylene glycols may be-added to the-greaseinplace-of the so.- dium naphthenate,- and the resulting T grease hasbetter mechanicalstability and, in-general, fails to disintegrate-underconditions where ordinary anhydroussodium base greases do disintegrate,

althoughthey havebeen prepared by the incor-- portion therein of ananti-disintegration materiaLas for example, sodium naphthenate. Withexceedingly-small percentages ofthe polyalkylene glycols, as forexample, .0l% to 04%, the greases are not capable of-' being cooledquickly within the spirit of the present invention, but asthe percentageapproaches and exceeds 0.05%, the

anhydrous soda basegreases'may-be quikly cooled as herein set forth.

Example- 4 The following batch was. mixed:

grams Stearic acid. 600(737'75). Sodium hydroxide. 82 (1.05%) Paraffinicneutral oil,] 100 vis.

at 100 F 2800(36%)' Coastal redv oil; 2000' vis. atv

The abovemass was cooked at= 3609 11; and

poured-into pans toa depth of 3 -to inches, and: showed upon coolingexcessive bleeding, about 10% or moreof the oil bleeding or separatingduringa-cooling-time of 12to 16 hours.

The samegrease, towhich'there was added .02%

of polyethylene glycolhavingan average molecular-weight of between 200to 7000' was cooked and cooled under the" same conditions as the greasewithout the polyethylene glycol, and therewas produced a perfectly dry,-substantially anhydroussodabase or sodazsoap grease having a. meltingpoint of 356 F. andan ASTM= penetration, after 60 strokes, of292decimi1limeters and;

after 300 strokes, 326 decimillimetersand acidity of 0.1 oleic acidequivalent;

Examples Asoda baseereaseqwas prepared from; the following, batch of.constituents:

Theabove. batchwas cooked at 360F. and poured into cooling pants inlayersof 3- [;"'to 4: in depth-,- the grease. being pouredatapprox-imately 350 This; greasewas cooled'inap proximately l'2to- 16hours and had an-ASTM penetration, after 60 strokes, of 264decimillimeters which within six hours--exposure to the rubbing actionof theShell Oil Company Roller-- Tester, softened; fromamicropenetration of 92:

to that of 233' decimillimeters.

The samebatch of constituents was mixed with ofpolyethylene *glycolhaving'an-average molecular weight of 1500; andthen cooked" 61-. in theusual manner. There: was; produced; grease having an ASTM penetration.afterrfip' strokes, o;f. 220 decimillimeters which increased insoftness, after 9 hoursin-ashell roller tester only from 74 to 104decimillimeters penetration as determined using the Shell Microcone.

The beneficial effects obtained from adding exceedingly small.percentages of polyalkylene glycols, as for. example, the higher.polyethylene. glycolsof the character herein setforthor the equivalentpolypropylene glycols, or the equivalent polybutylene, glycolsmay beobtained'using any of the prior art batches used'for the produc: tion ofanhydrous soda soap. greases. The re? marks made inconnection withExamples, 1 .to. 3. are also applicable to that form of. the invention.set forth in Examples 4 and 5. More specifi cally, it is desired topoint out that the fatty acid constituent, which may bea saturated fattyacid or an unsaturated fatty acid, which may be used in carrying out thepresent invention includes stearic acid, l2-hydroxy stearic acid, 9,10-dihydroxy stearic acid, 4-hydroxy palmitic acid; iso stearic acid,iso-palmitic acid, 12-hydroxy 9- oleic acid (ricinoleic acid), oleicacid, lineoleic acid, hydrogenated fish oil fattyacids, palm oil fattyacids, cotton seed oil' fatty acids. Further, abietic acid, and/or thecorresponding glycerides thereof, and/or naphthenic acidsmaylee-incorporated in the grease making batch.

used in grease making are, in general, the.satu.---

rated fatty acids containing up to 32 carbon atoms and usually from 14to 32. carbon atoms;

- and the unsaturated acids containing, up to 22.

carbon atoms and usually ranging from 18 to 22 carbon atoms. Insteadofusingthe fatty acids, the glyeerides thereof may be.=use d asfwell as.

themonohydric alcohol esters of said fattyacidsor the wax esters of saidacids. The saponifiable. constituent of the grease making batch may be avegetable oil or an animal oil or fat usually, used in the production ofanhydrous soda base. greases; In short, any of theprior artsaponifiablemedia may be used which are set forth in. Klemgards book entitled,Lubricating Greases; Their Manufacture and Use" (1937) published by theReinhold Publishing Company, New York; The saponifying medium may besodium-hydrox: ide or metallic sodium, and the present invention may becarried out when. using metallic, sodium inaccordance with thedisclosure of my.

copending application Ser. No. 625,966, now U. S;

Patent No; 2,445,935 grantedJuly-27; 1.948.

Ingeneral, the polymerized higher. polyajlkyle ene glycols havingbetween 2 and 6 carbon atoms 5 in the alkylene groups are effective incarrying:.

out .thepresent invention, but those'containing. the ethylene andpropylene groups are preferred; However, the butylene, amylene, andhexylene glycols may be used. The average molecular weight of thepolyethylene glycols used in carrying out the present invention may.vary from 200 to 7000 or 400 to-7000, the preferred molec ular weiglitvaryingfrom. 1000 to 4000; It appears that the most effective averagemolecular weight is about 1500.

Polyethylene glycol has the following formula:

41130 r-OH The formula for the polybutylene glycol is as follows:

C2114 CzH4OH (E2114 e-C2H4OH In all of the examples given, thepolyethylene glycol may be replaced by polymerized polypropylene glycolor polymerized polybutylene glycol, said glycols having an averagemolecular weight in excess of 200, and usually between 200 and 7000.

The greases of the present invention may carry a sodium soap in theamount in which it is customarily present in sodium soap greases, theprior art greases being well set forth in Klemgards book previouslyreferred to. More specifically, the soda soap greases of the presentinvention may carry from 1% to 50% of a sodium soap, but more usuallycarry from 1% to 15%, and, preferably, carry from 3.5% to l /2%, or

It is desired to point out that the higher polyalkylene glycols arecomposed of a mixture of several polymers, for example, polyethyleneglycol 400 consists of various glycols varying from a minor portion oftetraethylene glycol with increasing amounts of nona ethylene glycol andthen increasing up to the pentadecaethylene glycol. Therefore, it is theaverage molecular weight which is specified and wherein the presentspecification polyalkylene glycols or polyethylene glycols are referredto, they define the higher glycols having an average molecular weight inexcess of 200 and preferably in excess of 400, those with an averagemolecular weight in excess of 1000 being very effective in carrying outthe present invention.

In accordance with the present invention there has been provided ananhydrous reversible soda base lubricating grease, said greasecontaining from 1% to 50% of a soda soap and, preferably, between 3.5%to of a soda soap base. The anhydrous grease contains from about .01% to1% of a polyalkylene glycol of the character set forth. The anhydrousgrease becomes completely reversible when the amount of polyalkyleneglycol is around 05%. With all amounts of the polyalkylene glycol, thegrease becomes bleedless, and when the grease has present between about.05% to 1% or greater amounts, the grease is capable of being quicklycooled within the spirit of the present invention.

The invention in one of its forms comprises cooling a hot fluidanhydrous sodium soap lubricating grease to its solid state in thepresence of a polyalkylene glycol having an average molecular weight inexcess of 200, the amount of the polyalkylene glycol ranging from .01%to about 1%. The present invention is also directed to a method ofpreventing bleeding of oil from an anhydrous lubricating greasecontaining a lubricating oil base and a sodium soap by incorporating inthe grease from .01% to about 1% of a polyalkylene glycol having anaverage molecular weight in excess of 200. The method is also directedto accelerating the cooling of a hot liquid sodium soap lubricatinggrease through a cooling range of at least 200 F. to a solid stateadjacent room temperature and in the absence of any bleeding comprisingincorporating in the grease a polyalkylene glycol in an amount greaterthan .05%, said polyalkylene glycol having an average molecular weightin excess of 200.

The percentages and percentage ranges herein set forth are taken on theweight of the grease.

The laws governing the rate of cooling of viscous or solid systems, suchas a grease system, is Well set forth in a book entitled HeatTransmission" by William H. McAdams, Second Edition, McGraw Hill andCompany, Inc., New York, 1942. It is there stated that the heatconduction in greases follows an inverse relationship between thecooling rate and the square of the thickness of the grease slabundergoing cooling. For example, if the middle plane of the grease slabcools in forty minutes, said grease slab having a thickness of 1", thena slab of thickness will cool in ten minutes, and a slab of thicknesswill cool in 2 minutes. In other words, by doubling the thickness of thegrease layer, the time for cooling is not doubled, but quadrupled.Actually, when cooling a grease slab from both sides from about 350 F.initial temperature to 100 F. final temperature in a stream of air of F.the actual cooling time will be somewhat longer due to (1) the heattransfer resistance of the air film limiting the rate of heat removal inthe short initial period of cooling the hot grease and (2) theliberation of the heats of gelation (crystallization) and transition ofthe anhydrous soap during certain stages of the cooling process, theabsolute amount of heat liberated being in proportion to theconcentration of the soap being present in the grease, and it has beendiscovered that this is substantially unaffected by the presence of thepolyalkylene glycols in the amounts stated.

In accordance with the present invention a hot grease in layers of aboutto about 1" will cool from about 350 F. or a little higher to a roomtemperature of F. in less than two hours; that is, between 30 secondsand two hours.

While in carrying out the present invention the raw materials are cookedtogether in the presence of the polyalkylene glycol, the latter may beadded to the cooled grease by agitation, and then the mass may be heatedto above 300 F. and allowed to cool. This will produce a grease whichdoes not bleed and which can be quickly cooled in layers of A to 1" inless than 2 to 4 hours. 1

During the cooking of the grease, there may be introduced therein smallamounts of any of the prior art aluminum or calcium soaps, and by smallamounts is meant less than 2% of any prior art aluminum soap or lessthan 2% of any prior art calcium soap, or the amount of prior artaluminum soap or prior art calciumsoap in the grease together may beless than 2%, and the properties of the grease which are conferredthereon due to the use of the polyalkylene glycols will be retained bythe grease. More specifically, the amount of the aluminum soap and/orcalcium soap may vary between 0.1% to 2% taken on the weight of thegrease. However, after the sodium soap grease of the present inventionhas been once cooked in the presence of the polyalkylene glycol andcooled, said grease can be mixed when cooled with any amount of aluminumsoap grease or calcium soap grease. For example, there may beincorporated into the soda base grease 1% to 70% of aluminum soap greaseor 1% to 70% of a calcium soap grease, or mixtures thereof, said greasesbeing incorporated into the cold sodium soap grease. Any of thepolyalkylene glycols herein broadly and specifically set forth may bemixed with each other in any proportion and used in the place of asingle polyalkylene glycol.

In the trade, the anhydrous soda base greases usually contain less than.25% of water.

I claim:

1. An anhydrous soda base lubricating grease containing .05% to about 1%of a polyethylene glycol having an average molecular weight in excess of200, said percentage range being taken on the weight of the grease.

2. An anhydrous soda base lubricating grease containing to about 1% of apolyethylene glycol having an'average molecular weight varying betweenabout 200 and about 7000, said percentage range being taken on theweight of the grease.

3. An anhydrous soda base lubricating grease containing from 05% toabout 1% of a polyethylene glycol having an average molecular weightvarying between about 1000 and about 4000, said percentage range beingtaken on the weight of the grease.

4. An anhydrous reversible soda base lubricating grease containing about1% to 50% by weight of a soda soap and about 0.01% to about 1% of apolyethylene glycol having a molecular weight greater than 200.

5. An anhydrous reversible soda base lubricat ing grease containing .1%to .3% of a polyalkylene glycol having an average molecular weight inexcess of 200, said percentage range being taken on the weight of thegrease.

6. An anhydrous bleedless reversible soda base lubricating greasecontaining about 0.01% to about 1% of a polyalkylene glycol in which thetotal carbon atoms present in the alkylene groups I 8. A substantiallyanhydrous bleedless soda base lubricating grease containing 01% to 05%of a polyalkylene glycol having an average molecular weight in excess of200, said percentage range being taken on the weight of the grease.

9. A substantially anhydrous bleedless soda base lubricating greasecontaining 01% to 05% of a polyalkylene glycol having an averagemolecular weight varying between 400 and Z000, said percentage rangebeing taken on the weight of the grease.

10. An anhydrous bleedless soda base lubricating grease containing .1%to .5% of a polyalkylene glycol in which the total carbon atoms presentin the alkylene groups varies from 2 to 6 inclusive, said polyalkyleneglycol having a molecular weight in excess of 200, said percentage rangebeing taken on the weight of the grease.

11. An anhydrous bleedless soda base lubricating grease containing .1%to .5% of a polyethylene glycol in which the total carbon atoms presentin the ethylene groups varies from 2 to 6 inclusive, said polyethyleneglycol having a molecular weight in excess of 200, said percentage rangebeing taken on the weight of the grease.

12. An anhydrous bleedless lubricating grease containing a greaseproducing amount of a sodium soap of 12-hydroxy stearic acid and havingpresent 01% to 05% of a polyalkylene glycol in which the total carbonatoms present in the alkylene groups varies from 2 to 6 inclusive, saidpolyalkylene glycol having a molecular weight in excess of 200, saidpercentage range being taken on the weight of the grease.

13. A lubricating grease composition consisting essentially of minerallubricating oil thickened to a grease consistency by the sodium soap ofsubstantially saturated higher fatty acids and containing about 0.1% ofpolyethylene glycol having a molecular weight of about 1000.

14. A soda soap base lubricating grease containing 0.05% to about 1% ofa polyethylene glycol having an average molecular Weight in excess of200, said percentage range being taken on the weight of the grease.

15. A lubricating grease composition comprising mineral lubricating oilthickened to a grease consistency by the sodium soap of substantiallysaturated higher fatty acids and containing about 0.05% to about 1% ofpolyethylene glycol having an average molecular weight between about 200and about 7000.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,398,173 Brunstrum et a1 Apr. 9, 1946 OTHER REFERENCESSynthetic Organic Chemicals, 12th edition, pamphlet by Carbide andCarbon Chemicals Corp., New York, N. Y., pages 19 to 23, pub. July 1,1945.

14. A SODA SOAP BASE LUBRICATING GREASE CONTAINING 0.05% TO ABOUT 1% OFA POLYETHYLENE GLYCOL HAVING AN AVERAGE MOLECULAR WEIGHT IN EXCESS OF200, SAID PERCENTAGE RANGE BEING TAKEN ON THE WEIGHT OF THE GREASE.